Xenon lamps of interest herein are short arc or compact arc lamps having an arc gap between the cathode and anode electrodes of less than 14 mm. These lamps are useful where a high intensity point source is needed. Typical examples of such use are in searchlights, solar simulators, medical instrumentation, photoresist exposure and video and film display projectors.
A xenon short arc lamp is filled with a xenon gas or another noble gas or mixture which will produce an essentially continuous spectrum of visible light. Short arc lamps have many uses and, without limiting these uses, the particular area of use described herein will be in lamphouses for cinema projection.
These lamphouses include, among other elements, a reflector/collector for collecting the optical radiation from a lamp, adjustable mounts for the lamp to focus the system so that the light goes through the aperture, an aperture through which the collected light is reflected, a lens beyond the aperture for collecting and focusing the light, and a power supply for operation of the lamp and lamphouse.
Some commonly used lamphouses for cinema projection are manufactured by Strong-Cinema Products, a division of Ballantyne of Omaha, Inc. and having an internet address of www.strong-cinema.com. Lamphouses are made for xenon short arc lamps having an output of 700 watts up to 10,000 watts and are designed to accept standard xenon short arc lamps.
There are various manufacturers of xenon short arc lamps, including, Osram, Ushio, Superior Quartz and Lighting Technology International (the Assignee of this application). These manufacturers, following what has become industry standards, manufacture various models of xenon short arc lamps. These models are categorized by wattage and mounting technique. Xenon short arc lamps for cinema projection lamphouses range from 500 watts to 10,000 watts and are typically mounted in a horizontal position in the lamphouse.
The lamps that have been manufactured in the past have an industry standard configuration and dimensions that fit within a useful range. In particular, the envelope of these lamps consists of a quartz glass housing having two cylindrical sections and a nearly spherical middle section. A useful and distinguishing measurement of the middle section is the ratio of the length (L) of the middle section to the diameter (D) of the middle section.
The length (L) is measured from the point of transition from the straight surface of a cylindrical section to the curved surface of the middle section at one end of the middle section to the transition at the other end of the middle section. The ratio of length (L) to diameter (D) of xenon short arc lamps for cinema projector lamphouses have not exceeded 1.45 as far as the inventor herein knows.
There is one exception to the upper ratio and that is for a lamp manufactured by Osram that is called a gap shortened (GS) lamp. The ratio of length to diameter for Osram's XBO 4200 W/GS lamp is approximately 1.871. This lamp has been used in specially modified lamphouses with attendant additional expense. In particular, the lamp has been advertised, since at least August 2002, for use with a revolutionary lamphouse conversion that replaces and repositions the reflector and replaces the xenon lamp. This has been stated by NCS Corporation of 14499 North Dale Mabry Highway, Suite 201, Tampa, Fla. in its TechnaLight high definition film presentation. The conversion involves replacing the old reflector with a new reflector in a different position and replacing the lamp holder.
Strong-Cinema Products of Strong International also put lamps having a length in diameter ratio greater than 1.6 in a lamphouse with a different reflector. This is set forth in the Strong-Cinema advertisements entitled Application Guide Number: AG-002 dated Aug. 12, 2003. Strong International has an office at 4350 McKinley Street, Omaha, Nebr.